1. Field of the Invention
The present invention relates to a system for the preparation of ceramic shell molds by coating wax masters with fine particles of refractory material to obtain ceramic shell molds for use in the investment casting process.
In the investment or lost-wax casting process, each wax mold is firstly dipped into a slurry containing a binder and a filler, the excess slurry being drained off from the wax master, and then the wax master wetted by the slurry is coated with a so-called stucco powder made of fine particles of refractory material followed by drying to form a coating layer of refractory material. The aforementioned step for the formation of coating layer is repeated until a coating layer having a desired thickness is formed. The thickness of the coating layer requisite for the ceramic shell molding process is different from that for the solid molding process. However, irrespective of whether the coating layer is formed for the ceramic shell mold or for the solid mold, the coating steps must be repeated for several times. Accordingly, improvement in efficiency of this coating step would provide great contribution to the improvement in producibility of overall casting process and also to the reduction in production cost.
2. Prior Art
One example of previously proposed automation systems for the preparation of ceramic shell molds comprises a conveyer, a slurry bath and a stucco powder bath sequentially disposed in this order along the conveyer, and an industrial robot. However, this known automation system has a disadvantage that it is inevitable to use the robot devotedly for holding each wax master for a considerable time to effect drainage of the excess slurry after the wax master is pulled out of the slurry bath. This results in down-time during which the operation of overall system must be stopped. For this reason, the production efficiency of this known automation system is not increased to a satisfactory level.